Donor-acceptor copolymers from cyclopentannulation polymerizations with dicyclopenta[cd,jk]pyrene and dicyclopenta[cd,lm] perylene acceptors

A series of donor-acceptor copolymers with dicyclopenta[cd,jk]pyrene and dicyclopenta[cd,lm]perylene acceptor units was prepared via palladium catalyzed cyclopenta-annulation reactions. The acceptor units were paired with diethynyl containing donor groups based on benzo[1,2-b:4,5-b’]dithiophene, thieno[3,2-b]thiophene, and 4-octyl-4H-dithieno[3,2-b:2′,3′-d]pyrrole to create six polymer variants. The cyclopentannulation polymerization resulted in copolymers with molecular weights (Mn) of 6–14 kDa and broad light absorption in the visible region with band gaps of 1.38–1.85 eV. The synthetic methodology, as well as optoelectronic properties, including thin-film absorption and cyclic voltammetry, of the donor-acceptor copolymers are presented.     

Spectral Analysis and Solvability of Volterra Integro-Differential Equations

Doklady Mathematics - Integro-differential equations with unbounded operator coefficients in a Hilbert space are studied. The equations under consideration are abstract hyperbolic equations...     

A spatiotemporal representation of the electromagnetic field radiated by short-pulse superwideband antennas

It is shown that two approaches can efficiently be applied to calculate impulse responses of antennas radiating superwideband signals. The simultaneous use of these approaches makes it possible to lucidly describe the operation of certain antennas and substantially simplify the calculations. The impulse responses of some short-video-pulse scanning array antennas and the shapes of radiated signals are calculated.     

Adaptive viewpoints for co-browsing on heterogeneous devices

Co-browsing is an activity in which a group of users navigate their way through of a set of Web pages together for a shared purpose. Effective co-browsing among users with different device capabilities requires a shared understanding of those Web pages. This paper demonstrates the concept of shared viewpoints (SVPs), and personal viewpoints (PVPs), for co-browsing, before detailing a framework for implementing these concepts. Finally, the effectiveness of the framework is presented through a perceptual experiment.     

Encapsulation and Ostwald Ripening of Au and Au–Cl Complex Nanostructures in Silica Shells

We report a general template strategy for rational fabrication of a new class of nanostructured materials consisting of multicore shell particles. Our approach is demonstrated by encapsulating Au or Pt nanoparticles in silica shells. Other superstructures of these hollow shells, like dimers, trimers, and tetramers can also be formed by nanoparticle‐mediated self‐assembly. We have also used the as‐prepared multicore Au–silica hollow particles to perform the first studies of Ostwald ripening in confined microspace, in which chloride was found to be an efficient mediating ligand. After treatment with aqua regia, Au–Cl complex is formed inside the shell, and is found to be very active under in situ transmission electron microscopy observations while confined in a microcell. This aspect of the work is expected to motivate further in situ studies of confined crystal growth.     

Note on B-splines, wavelet scaling functions, and Gabor frames

Let g be a continuous, compactly supported function on such that the integer translates of g constitute a partition of unity. We show that the Gabor system (g,a,b), with window g and time-shift and frequency-shift parameters a,b>0 has no lower frame bound larger than 0 if b=2,3,... and a>0. In particular, (g,a,b) is not a Gabor frame if g is a continuous, compactly supported wavelet scaling function and if b=2,3,... and a>0. We give an example for our result for the case that g=B/sub 1/, the triangle function supported by [-1,1], by showing pictures of the canonical dual corresponding to (g,a,b) where ab=1/4 and b crosses the lines N=2,3,.